1. Field of the Invention
The present invention relates to packet-based networks (e.g. Ethernet), and more particularly to a packet switch equipment based on a packet switch chip and a bandwidth control method using the same.
2. Description of the Related Art
Network switch devices based on a packet switch chip provide a port-based bandwidth limitation function by using functionalities provided by their own chip. The bandwidth limitation function provided by the packet switch chip enable users to set up a series control conditions regarding bandwidth limitation of the chip. Based on its hardware, the packet switch chip limits the use of packets that belong to a predetermined category up to a threshold in a specific scheme. It is to be noted that a user or operator must set up information regarding which category of packets are to be limited, i.e. a filtering criterion for determining packets to be subjected to bandwidth limitation, and information regarding the degree of bandwidth allowance, i.e. metering criterion, onto the packet switch chip.
Packet switch equipments also have a function of limiting the bandwidth based on all packets drawn in via a specific port. However, this function fails if a number of users are connected to a single port.
FIG. 1 is a block diagram showing the construction of a conventional packet switch equipment. Referring to FIG. 1, the packet switch equipment 10 has a packet switch chip 12 including a number of ports (e.g. eight) PORT 1 to PORT N. Each port is connectable to a number of subscriber terminals 40. In FIG. 1, the second port, PORT 2, is shown to be connected to a number of subscriber terminals 40 via a subscriber distribution device 42. The packet switch equipment 10 also has a memory 16 for storing information regarding control of packets and ports via the packet switch chip 12, a CPU 14 for controlling the overall switching operation of an Ethernet switch equipment 10 including the packet switch chip 12, and a communication channel 18 for communication with an operator terminal 30.
In the illustrated packet switch equipment 10 shown in FIG. 1, a number of subscriber terminals 40 are connected to a port, e.g., PORT 2. In order to prevent any device from exceeding a known limit, e.g., 5000 PPS (Packet Per Second), based on the source MAC (Media Access Control) address of each subscriber terminal 40, the operator must set up every source MAC address, connected to the port (PORT 2) in a manner that the source does not exceed the known limit.
However, when the conventional packet switch chip 12 is used to limit the bandwidth with regard to a number of users, the following problems occur.
First, in order to transmit packets from a number of users to a single port and prevent a specific user from using more than a predetermined amount of bandwidth or more, information regarding every subscriber connectable to the port needs to be set up. This is substantially impossible. In other words, when the amount of bandwidth used by specific source MAC is limited, based on the source MAC, with regard to packets flowing into the port, no setup regarding every MAC connectable to the second port can be made in advance.
Second, even when users connectable to a port have been determined in advance, the operator must manually set up information regarding the users onto the chip. The operator must also intervene when users are added or deleted.
Third, even when the number of users connectable to a port is limited and setups regarding them can be made, some portions of the bandwidth may not be used although they are available. For example, assuming that the total PPS which can be processed by a port is 10,000 and 10 users can use the bandwidth up to 1000 PPS, respectively, each user cannot transmit packets greater than 1000 PPS even when other users are not currently using the bandwidth. This is a waste of bandwidth.